Basics of SAD

The basics of SAD can be categorized into –

Introduction of System

• The term System is related to the Basics of SAD.
• The system is a general term applied in every field of our life.
• In general, a System is based on the Input-Process-Output (IPO model).
• System is a word derived from the Greek word ‘Systema’ which means an organized relationship among components.

Definition of System

• A system  is an organized collection of interconnected (or interrelated) interdependent components or elements that are designed and operated to work together to achieve a common or specific goal, purpose, objective, or set of objectives.
• A System may be defined as an orderly grouping of interdependent components linked together according to a plan to achieve a specific goal. Each component is a part of the total system and it has to do its own share of work for the system to achieve the desired goal. 

Characteristics/Properties of a System

There are the following properties of a system –

• Organization:
  • It implies structure and order.
  • It is an arrangement of components that helps to achieve objectives.
• Interaction:
  • It refers to the procedure in which each component functions with other components of the system.
• Interdependence:
  • It means that one related component of the system depends on another component.
• Integration:
  • It is concerned with how a system is tied together.
  • It is more than sharing a physical part. It means that parts of the system work together within the system even though each part performs a unique function.
• Central Objective:
  • It is quite common that an organization may set one objective and operate to achieve another.
  • Here, the important point is that the users must be aware of the central objective well in advance.

Features of a System

• A System can be a physical(such as a mechanical system) or abstract/conceptual entity(such as a software system), consisting of related inputs, processes, and desired outputs that interact with one another to achieve a specific function or objective.
• The study of systems is known as systems theory, which involves analyzing the behavior and interactions of complex systems and developing strategies for optimizing their performance.
• The elements or components of a typical system may include people, machines, tools, software, and other resources that are brought together and organized in a specific way to achieve a desired outcome.

Examples of a System

• Examples of systems are computer operating systems, information systems, transportation systems, financial systems, political systems, biological systems, railway reservation systems, school and college systems, Industry systems, and many others.

System’s Terminology

• System study is the skill of a systems analyst to know about a system. It involves the identification of each of the system’s characteristics such as inputs, outputs, processes etc.
• A System’s purpose is the reason for its existence and the reference point for measuring its success.
• A System’s boundary defines what is inside the system and what is outside. The boundary is between the firm and its environment.
• A System Environment is everything pertinent to the System that is outside of its boundaries.
• A System’s Inputs are the physical objects and information that cross the boundary to enter it from its environment.
• A system’s Outputs are the physical objects and information that go from the system into its environment.
• A Subsystem is a component of a System, even though it can also be considered as a system in its own right.
• A Project is defined as a sequence of unique, complex, and connected activities having one goal or purpose that must be completed by a specific time, within budgets, and according to specifications.
• A Risk is any unfavorable event or circumstance that can occur while a project is underway. If a risk comes true, it can hamper the successful and timely completion of a project. Therefore, it is necessary to anticipate and identify different risks, a project is susceptible to so that contingency plans can be prepared in advance to control the effects of each risk.

Classification of a System

• A typical System may be classified as follows:-
  • Formal or Informal Systems:
    • Formal Systems:
      • A Formal System is planned in advance and is used according to plan or
        schedule.
      • In this system policies and procedures are documented well in advance.
      • A real-life example of a Formal system is to conduct a scheduled meeting at the end of every month in which the agenda of the meeting has already been defined well in advance.
    • Informal Systems:
      • An Informal System is a system that is not described by procedures.
      • It is not used according to a schedule or plan.
      • It works on a need basis.
      • For example, Sales order processing system through telephone calls.
  • Physical or Abstract Systems:
    • Physical Systems:
      • Physical Systems are tangible entities that may be static or dynamic.
      • Computer Systems, Vehicles, Buildings, etc. are examples of physical systems.
    • Abstract systems:
      • Abstract systems are conceptual entities.
      • Examples are: Company
  • Open or Closed Systems:
    • Open Systems:
      • It is a system within its environment.
      • It receives input from the environment and provides output to the environment.
      • Examples are Any real-life system, Information System, organization, etc.
    • Closed Systems:
      • It is isolated from environmental influences.
      • It operates on factors within the System itself.
      • It is also defined as a System that includes a feedback loop, a control element, and a feedback performance standard. Performance Standard is defined as the objective that the System has to meet. A Feedback loop is defined as a portion of the System that enables the System to regulate itself. 
  • Manual or Automated System:
    • Manual Systems:
      • The system, which requires human intervention during processing, is called a Manual System.
      • Example: Face-to-face information centers at places like Railway stations etc.
    • Automated Systems:
      • The system, which does not require human intervention is called an Automated system.
      • In this system, the whole process is automatic.
      • Examples are Traffic control systems for metropolitan cities.
  • Real-time or Non-real-time System:
    • Real-Time System
      • A real-time system describes an interactive processing system with severe time limitations.
      • A real-time system is used when there are rigid time requirements for the flow of data.
      • A real-time System is considered to function correctly only if it returns the correct result within imposed time constraints.
      • Systems that control scientific experiments, medical imaging systems, industrial control systems, and some display systems are real-time systems.
      • There are two types of Real-Time systems. They are:-
        (a) Hard Real-Time Systems
        • These systems guarantee that critical tasks are completed on time.

   (b) Soft Real-Time Systems

• • • • • These are less restrictive types of real-time systems where a critical real-time task gets priority over other tasks and retains the priority until it is completed.
    • Non-Real Time System
      • A non-real-time system is a type of computing system where the correctness of the output does not depend on meeting strict timing constraints.
      • In other words, in a non-real-time system, there is no requirement for the system to produce results within specific deadlines or time bounds. Instead, the emphasis is typically on correctness, efficiency, and throughput.
  • Distributed or Centralized System:
    • Distributed System
      • A Distributed System in which the Data, Process, and Interface components of Information Systems are distributed to multiple locations in a computer network.
      • In this system, each processor has its own local memory. The processors communicate with one another through various communication lines, such as high buses or telephone lines.
      • The processors in a distributed system may vary in size and function. They may include small microprocessors, workstations, minicomputers, and large general-purpose computer systems.
      • The implementation of a distributed system is complicated but still is in demand. Some of the reasons are that modern businesses are already distributed. So, they need distributed solutions.
      • Advantages of Distributed System
        • Resource sharing
        • Computation speedup
        • Reliability
        • Heavy Communication.
      • Architecture of Distributed System
        The five Layers of Distributed System architecture are:-
        (a) Presentation Layer is the actual user interface. The inputs are received by this layer and the outputs are presented by this layer.
        (b) The Presentation Logic layer includes the processing required to establish the user interface.
        Example: Editing input data, formatting output data.
        (c) Application Logic Layer includes all the logic and processing required to support the business application and rules. Example: Calculations.
        (d) The Data Manipulation Layer includes all the commands and logic required to store and retrieve data to and from the database.
        (e) The Data Layer is actual stored data in the database.
    • Centralized System
      • A centralized system refers to a computing or organizational architecture where control, resources, and decision-making authority are concentrated within a single central entity or location.
      • In a centralized system, one main node or entity typically manages and coordinates the activities of other connected nodes or components.
      • While centralized systems offer advantages such as centralized control, resource sharing, and uniformity, they also have limitations related to scalability, reliability, and resilience.